Hemoglobin is a substance normally found in blood, and therefore detection of hemoglobin is one of the major methods for preventing and treating most illness at early stage, for example, stool occult blood testing for colorectal cancer, urine occult blood testing for bladder cancer or kidney cancer, sputum occult blood testing for bronchitis or lung tumor, etc.
In Taiwan, colon cancer rate has topped the cancer ranking for eleven consecutive years and is also the highest in the world. The incidence rate and death rate of colon cancer patients are respectively 18.6% and 20.1% in China, which both topped the rankings in the world. The incidence rate for colon cancer is 8% out of all cancer patients, which ranks fourth and the death rate ranks second in USA. Hence, improving the accuracy and convenience of stool occult blood test is an important factor for early treatment of colon cancer to lower the death rate.
However, conventional stool occult blood test requires collecting fecal specimen, sending it to the hospital for testing and waiting for the test result, which not only is inconvenient for the patient, the inability of testing-at-anytime also prohibits self-management of the patient for long-term health monitoring.
Moreover, the specimen collected for conventional testing is about 1 gram, but only 6 milligrams is used by the medical unit for testing. However, occult blood in the stool is not distributed evenly and so false negative result is easily concluded from the testing when the occult blood was not collected in the specimen. In addition, the bleeding of tumor or polyp is periodic, not continuous, and so it is possible that the tumor or the polyp did not bleed on the day of or the day before the collection of stool specimen, causing the test result to be false negative. Hence, the presence of occult blood in excreta cannot be accurately known and in turn the patient cannot be treated in time.